The invention relates to a method for determining the usage rate of a breaking hammer. A breaking hammer comprises a percussion device, as a result of the work cycle of which impact pulses are generated that may be transmitted to the material being processed by means of a tool so as to break the material. The operation of the percussion device causes physical phenomena that are measured with a sensor. By analysing the measuring results, it is possible to identify the work cycle of the percussion device and, on the basis thereof, define a quantity representing the usage rate of the percussion device. The usage rate determined during the operation of the percussion device is added cumulatively into a counter and may be expressed to the operator of the breaking hammer.
The invention further relates to a breaking hammer, the usage rate of which is determined by means of a measuring device. The invention also relates to a measuring device, with which the usage rate of the breaking hammer may be determined. The field of the invention is described in more detail in the preambles of the independent claims of the patent application.
Breaking hammers are used to break hard materials, such as rock, concrete, and the like. A breaking hammer comprises a percussion device for generating impact pulses to a breaking tool connectable to the breaking hammer. The breaking hammer is usually connected as an auxiliary device to a basic machine that may be an excavator, for example. The basic machine is typically equipped with an operating hour meter for monitoring the expiry of service cycles, among other things. However, determining the usage rate of the breaking hammer on the basis of the operating hours of the basic machine is very imprecise, because the breaking hammer is used only part of the time in comparison with the operating hours of the basic machine. Some of the operating hours of the basic machine are namely used in transferring the basic machine and positioning the breaking hammer by means of a boom. In addition, the basic machine, such as an excavator, may be used with other auxiliary devices, such as a bucket.
Thus, measuring devices have been developed to determine the usage rate of the breaking hammer independent of the basic machine. Publications U.S. Pat. No. 6,510,902 B1, U.S. Pat. No. 6,737,981 B2, and U.S. Pat. No. 6,170,317 B1 disclose arrangements for identifying the impacts of a breaking hammer by means of different sensors. In the publications, the servicing need of the breaking hammer is determined on the basis of the number of impacts. However, it has been noted that, in practice, it is difficult to reliably measure the number of all individual impacts. It has been noted that the obtained measuring results may be quite imprecise. In result, the services of breaking hammers are performed either too late or too soon. Further, publication GB 2 442 629 A describes measuring the pressure of the pump operating the breaking hammer and determining the operating time, that is, impact time, of the percussion device on the basis of the pressure. Publication US 2003/0 110 667 A1 describes furnishing the pressure channel of the breaking hammer with a pressure switch, with which the operating time of the percussion device is determined. However, loads may be directed to the breaking hammer even when it is not generating impacts. These loads cannot in any way be taken into account in the prior-art solutions. Thus, the above-mentioned arrangements based on measuring the impact rate or time do not provide sufficiently precise information on the load directed to the breaking hammer for the purpose of proactive maintenance, for example.